Special Class

A. Shishkov

Special class of ground attack
('Stormovik' in Russian classification - A.S.) aircraft, specialized for attack of ground targets from
extremely low altitude always attracted attention of aviators. It was developed in a variety of different
projects starting as early as
1912.

After the Civil War
(1917-
1922 - A.S.)
special squad of "boevick"'s (exactly - fighter, AS) was created within outnumbered
Soviet VVS under special order of "Narcomvoenmor" (people's commissar
of military and naval - AS). This detachment became a prototype for future stormovik detachments. It was armed with
ordinary R-1 reconnaissance aircrafts. New practical operation methods vere summarized in late
1927
in the first issue of "Lessons
(Nastavlenija ?) of attack aviation".

Efficiency of stormoviks were highlighted by summer
1928
Kiev military exercises. After this new similar squads were
created. Those were equipped with new R-5 reconnaissance aircraft.

Design of specialized stormovik started from hammering out
TTT. Those were developed by 1st section
of Science-Technical commetee of VVS command.
This section was lead (since
1926)
by young
VVS academy graduate
S.V.Ilyushin.
First experimental planes were TSh-1, TSh-2 and
TSh-3. Those were not a complete mess, but suffered from heavy passive
external 'hanged' armor (adding 400-900kg) and weak engines of 20th-30th. As a result this class
of stormoviks had no chance for recognition.

At the same time military experts worldwide raised opinion that stormovik should
be a multi-purpose aircraft, or aircraft of so called combined type. It supposed to serve as a recco,
light bomber and just 2-seat escort fighter.

In the beginning of
1936
in Soviet Union several design bureaus initiated creation of multi-purpose aircrafts. There was a
contest between design bureaus lead by
D.P. Grigorovich,
S.A. Kocherigin,
I.G. Neman,
N.N. Polikarpov and
P.O. Sukhoi.
This secret project was named 'Ivanov'.
Polikarpov's
team also was busy with building new dive bomber VIT-1.
S.V.Ilyushin,
formally in charge for design, building and production of his first military aircraft
DB-3, did not take official part in this job. Nevertheless,
he started his own research of armored stormovik parameters and design.

At last at January 1938
designer came to government with proposal for realization of his project : two-seat (pilot
and gunner) armored stormovik, with combat efficiency outclassing aircrafts created under
'Ivanov' project.

Armored stormovik of
S.V.IlyushinTsKB-55 was a two-seat low wing monoplane with
retractable gears. In flight main gears were semi-hidden in wing nacells. Aircraft planned to have single
AM-35 liquid cooling engine with take off
power 993kW (1350hp), developed by A.A. Mikulin team. The key design solution was
slick armor fuselage, protecting all important components: crew, engine, gas and oil systems.
Armored fuselage was actively included into stress distribution scheme. Front section
carried load of engine, reductor (gear box) and cooling system. Central section was loaded with
crew, rear defence gun turret, wings and tail section.

It was the first case in the USSR when clear armor K-4 was used on stormovik.
Frontal sections of pilot canopy were made of this armor. Parts of aircraft not protected by armor
where designed to survive severe combat damages: Tail section had active skin supported with
stringers, wing and tailplane had 2 spars, tail fin was a single piece with fuselage. Fact that
main gears were not completely hidden in wing nacells allowed to ground aircraft with minimal damage
on any unleveled opening without main gear extraction. Weight-saving loaded armoring provided sufficient
room for heavy powerful attack armament.

Originally planed armament was 5 ShKAS
7.62mm machine guns, including 4 fixed in wing and one for rear defence on a turret. Bombs
(400kg) were located in 4 inner wing bays, where bombs were partially shielded by armor. There
were special armor shields in front of them. In overloaded option additional 200kg of bombs could
be attached under the wings (on wing stinger separating bomb bays).

Ilyushin's proposal was accepted, and on the May 5th,
1938 final design and production of armored stormovik
TsKB-55 with military designation
BSh-2 was included into experimental production plan.

The first flight of TsKB-55 #1 took place at October 1st,
1939 under supervision of famous test-pilot V.K.
Kokkinaki. At December 30 he tried the second TsKB-55 also.

State commission tests of BSh-2
(TsKB-55 #2) started at April 1, 1940.
General conclusion of military experts was positive, but some weak point were cleared. Those were : low speed on
ground level (326km/h) and restricted pilot's view (by huge engine).

On the final stage of refinement
S.V.Ilyushin
received suggestion to rebuild aircraft into single-seater, to install two PTB-23 (designer Ja.G. Gaubin)
23mm guns and two ShKAS machine guns, also enforcing
armoring of aircraft.

Aircraft TsKB-55 #1 was urgently rebuilt. It received a new designation
TsKB-57. The first test flight took place at October 12,
1940 under supervision of V.K.Kokkinaki. He was one who completed factory
tests in extremely compressed period - only 40 flight days. He mentioned that aircraft flight control is extremely simple
and has no 'peculiarities'. Maximum speed reached on ground level was 423km/h and on ceiling altitude - 437km/h,
quite high for 1940.

Stalin's directive to start mass production of aircraft was signed in November
designated Il-2, and under this designation it came to state approval test.

The first mass-production Il-2 was produced in March
1940, as short as in 3 months after
documentation was received by factory. During production period aircraft artillery was improved after arriving of powerful
23mm gun VJa-23 (designed by A.A. Volkov and S.Ja. Jartcev). Projectiles of this gun penetrated 25mm steel
armor from distance 400m. It was those guns Il-2 passed state approval tests.

Both were significantly weaker than Il-2 by their
armament, flight characteristics and design concept.

Il-2 obtained its combat trial on July 1, 1941
near town of Bobrujsk and Berezina river. Dependability, firepower, invulnerability for handgun (and generally
small anti-aircraft gun) fire made Il-2 a weapon of terror, just in hands of unskilled pilots. Combat experience
instantly highlighted also one significant disadvantage (predicted long ago by
S.V.Ilyushin) - vulnerability from fighter attacks from rear hemisphere.
Starting form the very first days of war design bureau received numerous suggestions from combat pilots to install
remotely controlled machine gun or gunner's cockpit for rear protection, as it was done on experimental
TsKB-55.

In July 1941 in 4 months after start of mass
production, factory produced about 300 Il-2's/month. But rapid advance of enemy ground troops endangered
production facilities of Il-2 and specially engines. It became
necessary in extremely short time to investigate possibility to accommodate aircraft for air-cooling engine
M-82, manufactured far behind front lines. As soon as September 8,
1941 test-pilot V.K. Kokkinaki made the first test of
Il-2 with new engine, and within 8 days completed
factory test program.

Evacuation delayed state commission tests, which took place in February-March
1942. Those test confirmed factory results. At that
time production of both Il-2 and AM-38
engine had full steam on new built factories.

At the same time it became clear that armor-shielded liquid-cooling engine is better solution
that unprotected air-cooling engine, despite its better survivability in case of combat damage. Despite
Il-4 (Il-2M82) with M-82 engine was
recommended for mass production, only one experiment aircraft was built.

Only in the early 1942S.V.Ilyushin
received order to design two-seat version of Il-2
with defence weapon and introduce it into mass production without interruption of factory conveyor (?).

So option of rear gunner cockpit with defence weapon was developed with
minimal changes in aircraft design. Flight weight was increased only by 270 kg.

In March 1942 2-seat
Il-2 came under factory tests. If was found that
maximum speed of aircraft significantly decreased. Stormovik became more tough to control,
specially during take-off and landing. AM-38 required to became more powerful. Fortunately,
team of A.A. Mikulin solved this problem very quickly.

Two-seater Il-2's with new AM-38 meet
first combat on Central Front October 30, 1942
during attack of enemy airfield near Smolensk. High combat efficiency of two-seaters was noticed
instantly. Just during combat tests period gunners shot down 7
Bf 109
and repelled numerous fighter attacks.

Starting January 1943 airforce
started to receive IL-2 with improved supercharged AM-38F
engine, what further improved speed, maneuverability and take-off/landing performance. New engine had
take-off power 1250kW (1700hp), which could be increased in combat for a short period up
to 1309kW (1780hp).

The second cockpit lead to Center of gravity shift back (~3.5%) and degrading of
longitudinal static stability. This unpleasant effect was eliminated by increase of wing sweep to
15°. But mass production of Il-2 with swept leading edge ('arrow')
wing started only in the late
1943.

Other direction of Il-2 modifications was
gaining of its attack firepower. Starting at the end of
1941
Ilyushin's OKB (Osoboe Konstruktorskoe Bureau, Special Design
Bureau - AS) studied options of installing two 37mm guns Sh-37 (B.G. Shpitalnyj) on single-seat
Il-2. But this modification failed to became wide-used because low
reliability of Sh-37 guns. In addition, low placing relatively to aircraft center of gravity
lead to 'dives' during fire and to lower fire accuracy.

In March-April
1943
2-seater
Il-2 with AM-38F was tried with modest 37mmNS-37 guns
developed by A.E. Nudelman team. This modification was tested in combat in Kursk Battle in July
1943.
High efficiency was demonstrated during
operations against enemy tanks and motorized infantry during this battle. Captured Nazi soldiers
confirmed that their forces suffered heavy losses from aircrafts with 'big gun'.
Il-2 with NS-37 was able to destroy famous
German Tigers with its gunfire...

In the beginning of
1945
45mm guns NS-45 were installed on Il-2.
Aircraft with those guns passed flight test successfully, but there were no mass production.

Rocket armament was also modified. Starting
1942Il-2
was equipped with rocket missiles RBS-82 or RBS-132 (with armor-piercing warhead and powerful
rocket engine) for more efficient destruction of enemy tanks. Efficiency of armored vehicle
destruction with Il-2 gained dramatically after introducing
of compact anti-tank bombs PTAB-2.5(-1.5) with cumulative action, developed by I.A. Larionov. Up
to 192 such bombs could be housed in four cassettes, installed in bomb bays. If hits target, PTAB
was able to burn through 70mm armor. Those bombs were tested first time during same Kursk
Battle. During first five days attackers from 291th storm division destroyed and damaged 422
enemy tanks.

There vere more modifications of Il-2.
For artillery spotting and reconnaissance Il-2KR
was used starting summer
1943.
It had same
design and arming, but had modified cockpit equipment, fuel system and armoring.

In
1943
small series of trainers
UIl-2 were manufactured with re-equipped rear cockpit, allowing to correct pilot's errors.

Il-2 had unique design as no other
aircraft in service during WWII. No any other country had such a weapon. Developed in
Germany (at the same time as Il-2) armored attacker Henschel
Hs 129
at the moment of German attack against USSR was not in combat ready conditions. Moreover,
Luftwaffe command relied completely on dive bomber Junkers
Ju-87 'Stuka'
and did not make any attempts to replace it until
1941.
Reason for this overconfidence was that this plane did very well during blitz-campaigns on the West Front.
In early period of Great Patriotic War it was a big mess for Soviet Union also. But later heavy losses of
'Stuka's in USSR forced
Germany to accelerate development of
Hs 129.

Starting early 1942 small
amount of those aircrafts participated in combat. Despite well armored cockpit, engines of
Hs 129
were vulnerable, and general flight performance was quite poor. Together with absence of
defence weapons it resulted that
Hs 129
(869 produced) was almost completely eliminated by Soviet fighters. At the same time Soviet
industry supplied army with 36163 Il-2's...